Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues	$ 482,522	$ 518,585
Costs and expenses:
Cost of sales	360,768	388,894
Selling, general and administrative	76,332	77,617
Amortization expense	3,729	3,156
Total costs and expenses	440,829	469,667
Earnings (loss) from operations	41,693	48,918
Other expenses and income:
Interest expense	7,679	7,054
Interest income	(62)	(58)
Other income, net	(302)	(697)
Total other expenses (income), net	7,315	6,299
Earnings (loss) before income taxes	34,378	42,619
Income tax expense (Note 1)	12,709	16,198
Net earnings	$ 21,669	$ 26,421
Net earnings per common share, basic (Note 6)	$ 0.56	$ 0.63
Net earnings per common share, diluted (Note 6)	$ 0.54	$ 0.60
Weighted-average common shares outstanding, basic (Note 6)	38,308	42,114
Weighted-average common shares outstanding, diluted (Note 6)	39,806	44,045
Common Stock, Dividends, Per Share, Declared	$ 0.31	$ 0